Can light ease pain of migraines?

Migraines are not often well controlled with medication. For some people, it may seem like nothing can stop the pain and sensitivity to light. But what if light itself was the key to getting relief?

Researchers used optogenetic manipulation to attempt to do just that.

Optogenetics, the use of light to control neuronal activity in the nervous system, is a technique that can produce gain or loss of function in specific signaling, and recently has shown promise in restoring vision and possibly even fighting psychiatric disorders.

As the name implies, the technique combines the stimulation of light of certain wavelengths with gene encoding for light-sensitive proteins to specifically regulate neuronal function. In this case, it allows for very precise control of activities of neural circuits in the central nervous system.

“If we can use optogenetic stimulation to manipulate neuronal activities in the neural circuits that contribute to the development of migraines, we could possibly reduce migraine headaches,” says Feng Tao, associate professor of biomedical sciences at the Texas A&M University College of Dentistry.

Of course, neurons don’t generally have light-sensitive proteins, so scientists use a specially engineered virus to express certain specific genes that code for these proteins that can then be activated with a laser implanted in the brain. After laser fiber implantation in an animal, researchers can activate the laser at different wavelengths to either excite or inhibit neurons in different brain areas while the animal is awake and moving around.

“A certain light-sensitive protein will only be activated with blue light and will then excite a neuron in the brain, while another type of light-sensitive proteins will only be activated with yellow light, and will then inhibit a neuron in the brain,” Tao says. “This way, we can regulate—either excite or inhibit—the neuronal function.”

Such a system allows for very precise control, neuron by neuron, that can be turned off and on at will.

Although at the moment, the laser still has to be controlled manually, the researchers hope to collaborate with electrical engineers to eventually be able to put a sensor into the brain and then control it wirelessly.

“This technology won’t just be used for biomedical research,” Tao says. “We hope we will be able to move it into clinical trials to treat intractable pain.”